An IEEE 802.11a protocol is a new specification that represents the next generation of Wireless Local Area Networks (“WLANs”). The IEEE 802.11a protocol uses 300 MHz of bandwidth allocated by the Federal Communications Commission (“FCC”) for what is called Unlicenced National Information Infrastructure (“UNII”). A WLAN implementing the 802.11a protocol can transmit at rates up to 54 Mbps.
The 300 MHz of bandwidth is divided into three 100 MHz bands, each one having different regulatory limitations. The first or lower band (“UNII-1”) (i.e., from 5.15-5.25 Gigahertz (“GHz”)), may transmit at a maximum power of 50 milliwatts (“mW”) and only use an antenna that is “captive” (i.e., internal or fixed) to a transmission unit (e.g., a mobile unit (“MU”) or access point (“AP”)). The second or middle band (“UNII-2”) (i.e., from 5.25-5.35 GHz) may transmit at a maximum power of 250 mW. The third or upper band (“UNII-3”) (i.e., from 5.725-5.825 Ghz) and use the internal or external antenna, may transmit at a maximum power of 1 W. Each of the lower and middle bands (i.e., UNII-1 and UNII-2) has four operating channels. These regulatory specifications have been determined by the FCC and the use and limitations of the bandwidth may vary from country to country.
When installing the WLAN several APs may be necessary to optimally cover a desired area. Each AP is assigned a specific channel to communicate with MUs so that there is no interference with the other APs communications. If more than four channels are necessary to prevent an interference (e.g., eight APs are needed to cover an area and all the APs must use different channels), then the WLAN must use UNII-1 as well as UNII-2 channels. Due to the “captive” antenna regulatory requirements for UNII-1, a different AP which uses UNII-2 channels must be used. This sacrifices the versatility of purchasing a single AP product that can be used for all wireless networking needs.
Alternatively, only AP units with “captive” antennas may be used for all channels. Such AP units sacrifice improved coverage that may be achieved when using UNII-1 and UNII-2 channels with external antennas. Therefore, there is a need for APs that can comply with the FCC regulation of “captive” antennas for UNII-1 channels with the flexibility of using external antennas for UNII-2 channels. Similarly, there is a need for APs that have the flexibility to comply with the varying regulations of different countries for the UNII-1 and UNII-2 bands.